1. Technical Field
The present invention relates generally to a focused ion beam apparatus that can cut off a micro sample-piece including an observation target portion from a sample by using a focused ion beam.
2. Description of the Related Art
For example, as a method of analyzing or observing an internal structure of a sample such as a semiconductor device, etc. or performing a three-dimensional observation thereof, a method of cross-section processing and observation (for example, refer to Patent Document 1) is well known. The method includes: by using a composite charged particle beam device having a focused ion beam (FIB) column and an electron beam (EB) column, conducting both cross-section processing using a focused ion beam (FIB) and scanning electron microscopy (SEM) observation using an electron beam (EB) irradiating a cross section.
The method of cross-section processing and observation is a method called “Cut & See” in which cross-section processing using a FIB is referred to as “Cut” and cross-section observation using an EB is referred to as “See”, Cut and See are repeated to obtain a three-dimensional image. In the method, by using the obtained three-dimensional image, it is possible to view a three-dimensional shape of a target sample in various directions. In addition, it is possible to reproduce an arbitrary cross-section image of a target sample, something impossible using other methods.
In the meantime, a secondary electron beam diffuses in SEM, and thus there is a limit to high magnification (high resolution) observation, and obtained information is limited to around the surface of a sample. Therefore, transmission electron microscopy (TEM) that transmits electrons through a sample processed in a thin film shape is well known. With TEM, it is possible to observe an internal structure of a sample, and to obtain an observation image with high magnification (high resolution) in comparison with SEM. The above-described cross section obtaining processing using an FIB may be applied to obtain a small sample (hereinafter, referred to as a micro sample-piece) processed in a thin film for TEM.
However, generally, it is desired for TEM to be performed under a high voltage and high vacuum in comparison with SEM. Therefore, a TEM apparatus is larger than an SEM apparatus, and it is difficult to integrate the apparatus for TEM with an FIB device. For those reasons, in a case of that a micro sample-piece, which is obtained by cross section processing using an FIB, is used as an observation sample for TEM, it is generally known that configurations can easily move the sample between the FIB device and the TEM apparatus by using a common sample holder for an FIB device and a TEM apparatus (for example, refer to Patent Document 2).
In a focused ion beam apparatus disclosed in Patent Document 2, an FIB micro sampling method is applied. In the method, FIB processing and mechanical probe operation are organized. In addition, a portion for analysis is cut off from a sample to obtain a micro sample-piece, and is placed on a sample tray referred to as a mesh for TEM analysis. A common side-entry-type stage for the FIB device and the TEM apparatus is provided in order to prevent a mesh from being replaced onerously due to moving a sample between the FIB device and the TEM apparatus. In addition, when a micro sample-piece is cut off from a bulk sample, processing is performed by using a sample tray for an FIB such that a side-entry-type holder is moved to an evasion position. When the micro sample-piece is fixed to a mesh on the side-entry-type holder, the sample tray for an FIB is moved to an evasion position.